Voltage regulator



Aug. 25, 1936.

B. M. LEECE VOLTAGEYREGULATOR Filed Dec. 4, 1933 illlll III PatentedAug. 25, 1936 UNITED STATES PATENT OFFICE VOLTAGE REGULATOR Bennett M.Leece, Cleveland, Ohio, assignor to The Leece-Neville Company,Cleveland, Ohio, at corporation of Ohio Application December 4,1933,Serial No. 790,813 14 Claims. (01. 171-229) This invention relatesgenerally to voltage regulators and, more specifically, to an improvedform of voltage regulating means which is suitable for use with avariable speed generator such as may be employed in a vehicle lightingand battery charging. system or in various. other types of generatingsystems. The invention relates further to a vibratory voltage regulatorof the general type disposed in my prior Patent 1,540,698,

granted Jun: 2, 1925, but is an improvement over the device of thispatent.

E-ieretoiore, in the construction of voltage regulating devices, it hasbeen generally the custom to construct the regulator with its variousparts, and particularly its regulating resistance, designed andproportioned in accordance with the characteristics and requirements ofthe particular generator with which the regulator is to be used.Regulators thus designed for use with particular generators have beenmore or less limited in application to motor vehicles in the truck andbus class, but a growing demand for voltage regulators in the passengercar class of vehicles has demonstrated the need for a regulator which,within a particular class of vehicles, will be'more or less generallyapplicable to diiierent, makes and types of generators.

It is, therefore, an object of the present inven- I tion to provide animproved form of regulating device, of the vibratory type, wherein afield regulating resistance is employed having a relatively hightemperature coeflicient so that the device will be self-adjusting and,therefore, selfaccommodating to the varying characteristics of thedifferent types of generators to which the device may be applied.

Another object of the invention is to provide an improved regulator ofthe type mentioned em-" voltage of the generator whereby the regulatoris self-accommodating to various types of generators without alteration.

Still another object or this invention is to provide an improved form ofvoltageregulator of the vibratory type which is applicable, withoutalteration, to various difierent makes of generators within a givenclass and which is of very compact and economical construction andcapable of operating very eificiently for effectively maintaining theterminal voltage of the generator with- 5 inrelatively close limits andto accomplish this function with a minimum amount of sparking at thecontacts.

Other objects and advantages of this invention will be apparent from thefollowing description, 10 when taken in conjunction with theaccompanying sheet of drawing, wherein Fig. l is a diagram illustratinga generating system which embodies my novel regulating means. I

Fig. 2 is a diagram illustrating another generating system embodying mynovel regulating means.

Fig. 3 15 a diagram illustrating the, same system as in Fig. 1 but withthe generator shown as a 20 conventional two-brush shunt machine.

Detailed reference will now be made to the accompanying drawing whereinI have illustrated improved regulating means for use with variable speedgenerators and which, as mentioned above, 25 may be embodied in agenerating system intended for vehicle lighting and battery chargingpurposes, or which may be embodied in various other generating systems.

Referring first to the arrangement illustrated in Fig. l of the drawing,it will beseen that I have shown a generator Ill to which my voltageregulating device II has been applied. The generator illustrated in thisinstance is a generator of the three-brush type having an armature l2and a field winding l3, although the invention hereinafter to bedescribed is also readily applicable to generators of the conventionaltwo-brush type. The generator I0 is here shown as having main brushes l4and I5, and anauxiliary or third brush it to which one end of the fieldI3 is connected by the conductor I1. Load conductors l8 and I9 may beconnected, respectively, to the main brushes l4 and I! for supplyinggenerated power for the operation of lamps 20, for the charging of thestorage battery 2|, or for various other purposes. Suitable switch meanssuch as a conventional reverse current cut-out or the prior art, or asimple form of switch 22 may be provided for controlling the externalload circuit.

The regulator itself comprises an electromagnet 23, and a vibratoryarmature 24 which is actuated in response to changes in the energizationor the electromagnet. The electromagnet 23 is closed. This spring 2provided with a suitable magnetizable frame 28 on which the windings orcoils 2B and 21 are arranged. The, armature may be suitably mounted onthe frame 25 as by means of the flexible, electrically conducting,connection it.

The regulator ii is also provided with pairs of cooperating contactswhich are rendered efiective by vibration of the armature iorcontrolling the excitation of the field it, in a manner to be presentlyexplained. These contacts are here shown as comprising stationarycontacts 29 and 3d, and movable contacts ti and 32 which are carried bythe armature 2G for cooperation with the station= my contacts. Asuitable spring, such as the tension spring 33, may be connected to thearmature it for normally biasing the same in a direction to cause thecontacts 253 and St to be is of such character, however, that'when theelectromagnet 23 is suficient- 1y energized, the armature 2% will bemoved in opposition to the spring 83 to separate the contacts 29 and 3!and, in some instances, to close the contacts 30 and 32'.

.For varying the field excitation, I provide, a field regulatingresistance 35 which is adapted to be intermittently connected into andshort-circuited from the circuit of the field i3 by the opening andclosing oi the contacts 29 and 36. This resistance is also adapted to beconnected, alternately, into the circuit of the field i3 and anauxiliary load circuit across the main brushes of the generator, by theopening and closing oi? the contacts 36 and 32. Although fieldregulating resistances have been used heretofore as a part of voltageregulating devices, the present invention contemplates the employment ofa special form oi field regulating resistance which, as mentioned above,has a variable resistance value and the effective value of theresistance is dependent upon the terminal voltage of the generator. Aswill be seen from the circuit arrangements presently to be traced, theeffective value of the field regulating resistance 35 is such as toautomatically adapt the regulator, without alteration, to various makesof generators within a given class, and 1 thereby makes the regulatingdevice one of more or less universal application.

In the accomplishment of the end sought, namely that of rendering theregulator universally applicable to various makes of generators, Iemploy as the resistance having a relatively high temperaturecoeficient. Although various substances or various elements having thischaracteristic may be employed as this resistance, I find that goodresults can be obtained by the use of a tungsten filament lamp as thisresistance. Good results can also be obtained when the resistance 35 isconstructed as an iron wire resistance device.

Reverting temporarily to the construction oi the regulator l LI wish topoint out that the electromagnet 23 may be variously constructed, but inthis instance I have shown the electrcmagnet as embodying the coils 2tand 2! which correspond respectively with the coils 2i and '22 or myabove cited prior patent. The coil 26 is a voltage coil which at alltimes responds to the terminal voltage of the generator, and the coil 2?is a secondary or auxiliary coil. These coils are arranged on the coreor frame 25 in additive re lation and their combined effect is toproduce an extremely rapid vibration of the armature 2 3 to causecorrespondingly rapid opening and closing of the cooperating contacts.

When the generator is first set in operation, the

storage battery M 35 an element or device contacts 29 and 3i are closed,by reason of the actionof the spring 33, and the armature 23 is thenconnected directly to the main brush it by the conductor 36 so that afull flow of field current travels through the conductor 36 and thearmature 2A to the field l3, and then through the conductor H back tothe third brush it. At the same time, the voltage coil 26 responds tothe terminal voltage of the generator by reason of this coil beingconnected across the main brushes it and i5. As seen in the drawing, oneend of this coil is connected to the brush Id through the conductors 31and 38, and the other end of this coil is connected to the brush l5through the conductors 39 and 36. While the contacts tfi'and 3i remainclosed the coil 27 is also energized directly from the main brushes ofthe generator by reason of the fact that one end of this coil isconnected to the armature 2 3 by the conductor it and the other end ofthis coil is connected to the conductor Ell.

When the speed of the generator has increased to the point where themagnetization of the frame 25, by the coils 26 and 21, attracts thearmature 24S and overcomes the spring 33, the contacts it and iii areopened. The opening of these contacts does not alter the circuit for thecoil 26, but does alter the circuit for the coil 21 the field I3. By theopening of the contacts 2% and 3! the resistance 35 is connected inseries with the field i3 and is also connected in series with the coil27. The field excitation is thereby decreased and, as a result of thefield magnetiza tion being decreased, the terminal voltage of thegenerator is lowered. The lowering of the terminal voltage of thegenerator, and the increase in the resistance of the circuit of the coil2? by reason of the resistance 36 being connected thereinto, decreasesthe magnetization of the frame 25 of the regulator to permit thecontacts 29 and St to be closed by the spring 33. The resistance 3% isthereupon short-circuited out of the field circult and out of thecircuit of the coil 2i, and the terminal voltage of the generator andthe magnetization of the frame 25 again increase.

Should the operating condition of the generator become abnormal, such aswhen the generator is driven at a relatively high speed or when theapproaches a condition of full charge, the regulator it then operates toexercise a greater regulating action on the generator.

During such abnormal condition the terminal voltage of the generator isrelatively high and the magnetization produced by the windings 26 and 2!is sufiicient to cause the armature 26 to opcrate intermittently onthe'contacts 25 and 3B or to operate altogether on the contact 30.

When the terminal voltage of the generator has increased sumciently tocause the contact 232 to engage the contact 30, the resistance 35 isconnected into an auxiliary load circuit across the main brushes of thegenerator. This auxiliary load circuit may be traced from the brush itthrough the resistance 35 to the armature 2d, and then through contacts32 and 3B and through conductor 38 to main brush It.

It will be observed from the novel circuit arrangement illustrated, thatwhen contacts 38 and 32 are closed the conductor load circuit justtraced substantially short circuits the field winding i3 and also themagnet coil 21. Since the windings i3 and 21 are of a relatively highresistance as compared to the conductor 38, it will be seen that whenthe contacts 3t and 82 are closed most of the current will flow Thecollapse of the main field of the generator causes a desired sudden dropin the terminal voltage of the machine, and the collapse of the magneticfield of the winding 21 causes a sudden decrease in the magnetization ofthe regulator. The drop in the terminal voltage of the generator, due tothe collapse of the field flux, also causes the magnetization of thevoltage coil 26 to be correspondingly reduced. This reducedmagnetization of the regulator allows the spring 33 to open the contacts30 and 32 thereby opening the short circuit and reestablishing the fieldcircuit through the resistor 35. Because of the sudden and substantiallycomplete deenergization of the windings l3 and 21 which occurs upon theclosing of contacts 30 and 32, I find that the armature 24 is vibratedat a very high rate and that very effective voltage regulation isobtained with only a small amount of sparking at the contacts.

It will also be observed that in the case of the third brush machineillustrated in Fig. 1, the establishment of the auxiliary load circuitby the closing of the contacts 30 and 32 causes the field winding to beconnected betweenthe main brush l4 and the third brush I 5. Since thelatter brush is positive with respect to brush l4 there will be atendency for a reversal of current fiow through the field Winding whichwould further accelerate the deenergization of this winding and thecollapse of the field fiux and thus increase the effectiveness'ofvtheregulation. Whether or not actual reversal of current. takes place inthe field winding will depend upon the resistance values employed, speedand load conditions and possibly other factors. I

As stated above, the resistance 35 has a relatively high temperaturecoefiicient and the effect of this on the operation of the regulator isto increase the resistance value of this element when the terminalvoltage of the generator increases. Thus, when the contacts 29 and 30are being rapidly opened and closed and the resistance 35 is 7 therebybeing intermittently connected into and short-circuited from the fieldcircuit, and the' terminal voltage of the generator tends to increase inspite of the regulation thereby produced, there will be an increasedfiow of current through the resistance element 35v and, because of itshigh temperature coefiicient, its resistance value will becorrespondingly increased. Such increase in the resistance value of thiselement amounts to inserting additional resistance into the field circuit and into the circuit of the coil 21 which affords additionalregulation of the generator.

When the contacts 30 and 32 are being opened and closed, as upon theoccurrence of an operating condition which requires additional voltageregulation, an auxiliary'circuit is intermittently established acrossthe main brushes, as explained above, with a portion of such circuitsubstantially short-circuiting the regulator winding 21 and the fieldwinding l3. Whenever the contacts 39 and 32 close, the resistance 35 isincluded in the auxiliary generator circuit just mentioned and wheneverthey open, this resistance is inserted in the field circuit. During suchtime as the regulator armature is operating on the contact 29 andconditions are such that the terminal voltage of the generator isincreasing, the resistance contact 5 i.

35 will be in the field circuit for an increased pe-' riod of timeandits resistance value will increase because of its positivetemperature coefiicient.

If conditions are such that the terminal voltage continues to increase,the armature of the regulator will ultimately operate on the contact 30,but as seen from the foregoing explanation of operation, when thecontact 32 first engages the contact 30 the resistance value of theelement 35 will be relatively high. If the terminal voltage of thegenerator continues to increase after closing of contacts 30 and 32 theresistance of the element 35 will increase further because of itspositive temperature coefflcient. It is desirable that the element 35have a relatively high resistance value when the contacts 30 and 32 areclosed, so as to prevent a heavy flow of current through the auxiliarycircuit of the generator which would otherwise cause burning of thecontacts. It will be noted however that when the resistance element 35is placed in the auxiliary circuit by the closing of contacts 30 and 32,its location in the circuit is such that it does not prevent anotherpart of the auxiliary circuit from'substantially short circuiting theregulator coil 2'5 and the field winding l3 as explained above.

It will thus be seen that the regulating resistance. is self-adjustingas to its resistance value, and because of this feature the regulatorcan be applied to different makes of generators and the self-adjustmentafforded by the resistance element will enable the regulator to adaptitself to eflicient cooperation with the generator to which it isapplied.

In Fig. 2 of the drawing I have illustrated regulating means which isgenerally similar to that illustrated in Fig. 1, but wherein slightlydifferent circuit connections are employed. In the arrangement ,of--Fig. 2 the generator 49 is a three-brush generator similar to thegenerator I8; of Fig. l, and is provided with a field 4i. One end of thefield windingis connected to the third brush 42 and the other end isconnected to the coil 43 of the regulator M. Load conductors 45 and 46are connected to the main brushes 4'! and 48 for supplying generatedcurrent to the lamps 49, to the battery 59, or for other uses.

The regulator 44 is also provided with a voltage coil 5i which isconnected across the main brushes 4! and 48, one end 01' the coil beingconnected to the brush 41 through the conductor 52, the stationarycontact 53 and the conductor 55, while the other end of the coil isconnected to the brush 48 through the conductors 55 and 56. The coils 43and 5| of the regulator 44 correspond generally as to construction andfunction to the coils 2'! and 26 of the arrangement shown in Fig. l. Avibratory armature 58 is arranged to respond to magnetization producedby the coils 43 and 5i so that contacts 59 and 60 carried by thearmature will cooperate, respectively, with stationary contacts 53 and6E.

Fig. 1, is arranged with the ends thereof connected respectivelyto thearmature 58 and the During low speed operation of the generator thecontacts 60 and 6! are intermittently opened and closed to therebyconnect the resistance 62' mittently opened and closed to therebyintermittently establish an auxiliary load circuit across the mainbrushes of the generator and in which A resistance element 62, similarto the resistance element 35 of I through conductor circuit is includedthe resistance element 62. The circuit which energizes the field 41while the contacts 60 and BI are open, may be traced from the main brush48 through conductors 56 and 83, and then through resistance element $2,armature 58 and flexible connection til to the magnet frame 66. Sinceone end of the winding 43 is connected to the magnet frame 55 thecircuit may be traced further through the winding 43 and through thefield windingdl back to the third brush 42. Likewise, the auxiliary loadcircuit which is connected across the main brushes while the contacts 58and 59 are closed, may be traced from main brush 48 through conductors55 and 63, and then through resistance element 52, armature 58, andthrough contacts 59 and 53 and 54 back to the main brush M.

The resistance element 62 is similar to the resistance element of Fig. lin that this element has a high temperature coemcient and, during theoperation of the regulator, the resistance or this element varies toprovide the correct amount of resistance necessary for efiicientcooperation between the regulator and the particular generator to whichthe regulator has been applied. Thus, during the operation of theregulating meansof Fig. 2, an increase in the terminal voltage of thegenerator will tend to maintain the contacts Eli and Bi separated duringa longer period of time but, during that period, current flows throughthe resistance 62 since it is then in series with the field circuit, andthe greater the flow of current through the resistance element thegreater will be the increase in the resistance value of this element.Similarly, when the speed of the generator is relatively high and thereis a tendency to maintainthe contacts 53 and 59 in closed relationduring a longer period of time, the correspondingly higher voltage ofthe generator will cause an increased current fiow through theresistance element 62, which is then connected into the auxiliary loadcircuit across the main brushes, and will result in an increase in; theresistance of this element. In both cases the increase in the resistanceof the element 82 enlarges the capacity or regulating ability of theregulator to such an extent that the terminal voltage of any type ofgenerator to which the device is applied is maintained substantiallyconstant for all operating conditions. i

In Fig. 3 of the drawing I have shown a 'system which is identical withthat of Fig. l with the exception that the generator. i0 is aconventional shunt machinev instead of a third brush machine and has thefield winding 13' thereof connected to the main brush l4. I'he functioning 01 the system of Fig. 3 is identical with that of the system of Fig.1 except that there is no tendency for a reversal of current in thefield winding, I

From the accompanying drawing and foregoing description it should now bereadily understood, that I have provided an improved form 0! voltageregulator wherein the regulating resistance element is a resistancehaving a high temperature .coeflicient, and that this characteristic ofthe re'-' sistance element causes a variation inthe eflfctive value ofthe resistance as changes occur in the operating condition of thegenerator. This 'f the resistance value of the self-adjustment theregulator to automaticallyelement enables accommodate itself particulargenerator to which the regulator is applied and, by reason of thisautomatic seliadjustment, my improved voltage regulator is unihaving acoil responsive of the generator and to the characteristics of theaosaoee tend to be limited to the precise arrangements of parts andcircuit connections illustrated and described. but regard my inventionas including such changes and modifications as do not involve adeparture from the the scope of the appended claims.

Having thus described my invention, I claim:

1. In combination, a generator having a shunt field winding, a regulatorcomprising a magnet to the terminal voltage a second coil in series withthe field winding, a vibratory member adapted to be actuated by themagnet, a pair of contacts in the field circuit and adapted to beintermittently closed and opened-by vibration of said member, aresistance element having its respective ends electrically connectedwith the contacts of said pair whereby opening of the contacts connectsthe resistance element in series with the field and with said secondcoil and closing of the conacts short-circuits the resistance, a thirdcontact with which one contact of said pair has vibratory cooperation,and circuit connections whereby engagement of said one contact and saidthird contact connects said resistance element in a circuit across theterminals of the generator with a portion of the latter circuit inparallel with the field winding.

2. In combination, a generator having a shunt tive ends electricallyconnected with the'contacts v of said pair whereby opening of thecontacts connects the resistance element in series with the field spiritof the invention and and with said second coil and closing or the con-;

tacts short-circuits the resistance, a third contact with which onecontact of said pair has 'vibratory cooperation, and circuit connectionswhereby engagement of said one contact and said third contactconnectasaid resistance element in a circuit across the-terminals of thegenerator, said resistance element having a high positive temperaturecoefiicient whereby its resistance value increases with an increase inthe terminal voltage of thegenerator.

3. In combination, a generator having a field winding, a regulatorcomprising a magnet having energizing coils and a vibratory memberadapted to be actuated by the magnet, a circuit for the field windingincluding a resistor, a pair of contacts adapted to be operated by thevibratory member for intermittently short circuiting said resistor outof the field circuit during one'condition oi-operation'oi the generator,said magnet coils including a voltage coil and acoil additive to thevoltage coil, a second pair of contacts adapted to be operated by thevibratorymember during another operating condition of the generator, andcircuit-connections controlled by the second pair. of contacts forsubstantially short circuiting} said field winding and said additivecoil.

In combination, a generator having a field winding, a regulatorcomprising a magnet having energizing coils and a vibratory memberadapted to be actuated by the magnet, a circuit for the field windingincluding a resistor, a pair of contacts adapted to be operated by thevibratory member for intermittently short-eircuiting said resistor outof the field circuit during one condition of operation of the generator,said magnet coils including a voltage coil and a coil additive to thevoltage coil, a second pair of contacts adapted to be operated by thevibratory member during 'another operating condition of the generator,and circuit connections controlled by the second pair of contacts forconnecting said resistor intoan auxiliary load circuit across thegenerator with a part of said auxiliary load circuit substantially shortcircuiting said field winding and said additive coil.

5. In combination, a generator having a field winding, a regulatorcomprising a magnet having energizing coils and a vibratory memberadapted to be actuated by the magnet, a circuit for the field windingincluding a resistor, a pair of contacts adapted to be operated by thevibratory member for intermittently short-eircuiting said resistor outof the field circuit during one condition of operation'of the generator,said magnet coils including a voltage coil and a coil additive to thevoltage coil, a second pair of contacts adapted to be operated by thevibratory member during another operating condition ofthe generator, andcircuit connections controlled by the second pair of contacts forsubstantially short circuiting said field winding and said additivecoil, said resistor having a relatively high positive temperaturecoeificient characteristic. I

6. In combination, a generator having afield winding, a regulatorcomprising a magnet having energizing coils and a vibratory memberadapted to be actuated by the magnet, a circuit for the field windingincluding a resistor, a pair of contacts adapted to be operated by thevibratory member for intermittently short-circuiting said resistor outof the field circuit during one condition of operation of the generator,said magnet coils including a voltage coil and a coil additive to thevoltage coil, a second pair of contacts adapted to be operated by thevibratory member during another operating condition of the generator,and circuit connections controlled by the second pair of contacts forconnecting said resistor into an auxiliary load circuit across thegenerator with a part of said auxiliary load circuit substantially shortcircuiting said field winding and said additive coil, said resistorhaving a relatively high positive temperature coeiiicientcharacteristic.

'7. In combination, a generator having a field winding, said generatoralso having a pair of main brushes and a third brush to which the innerend of the field winding is connected, a regulator comprising a magnethaving energizing coils and a vibratory member adapted to be actuated bythe magnet, said energizing coils including a voltage coil and a coiladditive'to the voltage coil, means connecting the outer end oi saidfield winding with one of said main brushes including a resistor, a pairof contacts adapted to be operated by the vibratory member forintermittently short eircuiting said resistor out of the field circuitduring one condition of operation of the generator, a second pair ofcontacts adapted to be operated by said vibratory member during anotheroperating condition of the generator, and circuit connections controlledby the second pair of contacts for intermittently connecting saidresistor into an auxiliary load circuit across the main brushes with aportion of such load circuit short circuiting said additive coil andconnecting the outer end of the field winding with the other of saidmain brushes.

8. In combination, a generator having a field.

winding, said generator also having a pair of main brushes and a thirdbrush to which the inner end of the field winding is connected, a

regulator comprising a magnet having energizing another operatingcondition of the generator,

and circuit connections controlled by the second pair of contacts forintermittently connecting said resistor into an auxiliary load circuitacross the main brushes with a portion .of such load circuit shortcircuit-ing said additive coil and corn necting the outer end of thefield winding with the other of said main brushes, said resistor havinga relatively high positive temperature coefiicient characteristic.

9. In combination, a generator having a field winding, said generatoralso having a pair of main,brushes and a third brush to which the innerend of the field winding is connected, a regulator comprising a magnethaving energizing coils and a vibratory member adapted to be actuated bythe magnet, said energizing coils including a voltage coil and a coiladditive to the voltage coil, a pair of contacts between which saidvibratory member is operable, a spring biasing said vibratory membertoward one contact of said pair, said one contact being connected withone of said main brushes, said field winding having the outer endthereof electrically connected with said vibratory member, a resistorelectrically connected with said one main brush and with said vibratorymember, one end of said voltage coil being electrically connected withsaid one 'brush and one end of said additive coil being electricallyconnected with said vibratory member, and means electrically connectingthe other contact of said pair and the other ends of said' magnet coilswith the other of said main brushes. 10. In combination, a generatorhaving a field winding, a regulator comprising a magnet havingenergizing coils and a vibratory member adapted 11. In combination, agenerator having a field,

winding, a. regulator comprising a magnet having energizing coils and avibratory member adapted to be actuated by the magnet, a circuit for thefield winding including a resistor, a pair of contacts adapted to beclosed by the vibratory member for intermittently short-eircuiting saidresistor out of the field circuit, said magnet coils including a voltagecoil and an auxiliary coil, a

second pair of contacts adapted to be operated,

byv the vibratory member, and circuit connections controlled by thesecond pair of contacts for connecting said resistor into an auxiliaryload circuit across the generator with a part of said auxiliary loadcircuit substantially short-circuiting. said field winding and saidauxiliary coil.

12. In combination, a generator having a field winding, a regulatorcomprising a magnet having energizing coils and a vibratory memberadapted to be actuated by the magnet, a pair of contacts adapted to beopened and closed by operation oi the vibratory member, a circuit forthe field winding including said pair of contacts, said magnet coilsincluding a voltage coil and an auxiliary coil,

a second pair of contacts-adapted to be opened and closed by operationofsaid vibratory member, and circuit connections controlled by said secondpair of contacts whereby closing of the latter causes the field windingto be substantially deenergized and one of said magnet coils to beshort-circuited.

13. In combination, a generator having brushes and a field winding, aregulator comprising a magnet having energizing coils and a vibratorymember adapted to be actuated by the magnet, a pair of contacts adaptedto be opened and closed by operation of the vibratory memberfla circuit.for the field winding including said pair of contacts, said magnetcoils including a voltage coil and an auxiliary coil, a second pair ofcontacts adapted to be opened and closed by operation of said vibratorymember, and circuit connections controlled by said second pair ofcontacts where- 5,

by-closing oi the latter establishesan external circuit across brushesof the generator with a portion of such external circuit substantiallyshort-circuiting said field winding and said auxiliary coil. l0 14. Incombination, a generator having a field winding, a regulator comprisinga magnet having energizing coils and a vibratory member adapted to beactuated by the magnet, a circuit for the field winding including aresistor, a pair 15 of contacts adapted to beclosed by the vibratorymember for intermittently short-circuiting said resistor out of thefield circuit, said magnet coils including a voltage coil and anauxiliary coil, 8.

second pair of contacts adapted to be operated 20 by the. vibratorymember, and circuit connections controlled by the second pair ofcontacts for connecting said resistor into an auxiliary circuit acrossthe generator with a portion of such auxiliary circuit in shunt relationto the field wind- 25 ing circuit, said resistor having a relativelyhigh positive temperature co-efflcient such that its resistance value isself-adjusting and is relatively high when connected into the auxiliarycircuit by said second pair of contacts.

'BE'I'I MZLEECE.

